ktvu's noelle walker shrive with an update. >> reporter: ken caltrans is making the most of this time without cars on the bridge. take a look behind me. at the moment this is one of the side projects that they are working on. they are installing new crash pads at tollgates. the main project, seismic retrofit that closed this bridge we're told is right on schedule. the san mateo bridge is the longest bridge in the bay area and this weekend it's also the quietest. okay, so that is not so quiet. but the traffic is. drivers are clogging other bridges and freeways because the san mateo bridge is closed for the weekend, so caltrans with reface a 60' section of it. >> we have replaced westbound and we have replaced three of the new seahawks and in the process of placing the fourth. >> reporter: these 14 by 34 bridge sections on top of that flatbed will be under commuters' tires on monday. caltrans is using a huge crane to put them in the piece by 4500-ton piece. >> when you are working with very, very heavy equipment you have to take things very slowly and carefully because of the safety fac